PROJECT SUMMARY The visual environment is crowded with information. Visual stimuli, frequently abundant with detail, inundate our retinae each waking moment. The ideal visual system would faithfully represent the bulk of this information; however, the primate visual system is inherently capacity limited. Consequently, vision must select a mere subset of the available stimuli for privileged downstream processing. This parsing mechanism is known as selective attention. While much is known about selective attention, the neurophysiological basis of `what to attend' and `what to ignore' is unresolved. It has been proposed that the N2pc component of the ERP relates to attentional selection whereas the Pd component relates to distractor suppression. Although these ERP components of attention have been identified, there is neither a clear picture of where exactly in the brain those signals originate, nor is there a thorough understanding of how those signals propagate throughout cortex to manifest into the observed behavioral phenomena. Visual areas, such as area V4, are the putative neural generators of the N2pc, but there have been no systematic studies demonstrating this. Similarly, attentional selection has been attributed to processes in frontal cortical areas, such as FEF. Therefore, it stands to reason that FEF and areas like V4 might interact to produce attention. To this end, the primary research goal of this training proposal is to understand how V4 and FEF interact to influence attention by employing a comparative electrophysiological approach in human and non-human primates. Specifically, the aims are 1) to elucidate electrophysiological markers of selective attention in human and non-human primates using scalp-recorded EEG, and 2) to use single-unit neurophysiological techniques to determine how these changes are instantiated at the level of individual neurons in areas FEF and V4. The primary training goal is to develop my expertise in both human and non-human primate electrophysiology by complementing my expertise in behavioral and cognitive psychology to directly bridge human and animal models of cognition, as well as affording a more direct and rapid translation of my basic research to clinically relevant applications.